The invention relates to devices for taking the square root of an input signal and, more particularly, to devices for providing an output pressure which is a function of the square root of an input pressure.
Current interest in energy conservation and variable volume control systems has given rise to a renewed interest in flow measurement and control. One of the simplest methods to measure the flow within a conduit or duct is to measure the pressure drop that occurs across an orifice, baffle or coil. The drawback of this approach, however, is that the output signal from this measuring device is a square root function since flow and pressure drop are related to one another by a square root function. For low flows, the pressure drop changes slowly, but for large flows the pressure drop changes rapidly. To overcome this problem, it has been traditional to use a square root extractor to provide a signal which is the square root of the output signal from the pressure measuring device and is, thus, substantially linear. The present square root extractors, however, are expensive and complex.
These prior art square root extractors specifically fall into several categories. First, there are those which use the input pressure supplied thereto for adjusting a fulcrum to mechanically extract square roots. Second, there are those which rely on the multiplication of forces acting on a balance beam.